Subducted slabs are stagnant in the mantle transition
Subducted slabs are stagnant in the mantle transition zone, and then collapsed into the lower mantle (from Fukao et al. 1992; 2001)
4. Birch’s Law • Birch’s Law – Birch (1961 b) VPと密度の関係式 “As a provisional hypothesis, it will be postulated that the velocity-density relations, as expressed above, hold for all changes of density in the Earth’s mantle, however produced. ” 圧縮による密度変化や化学組成が変わる(ただし平均原子量は不変)こと による密度変化は弾性波速度へ同じ変化をもたらす 平均原子量が同じ異なる物質のBirchの関係式の傾き 最密構造(例:Corundum, rock salt, perovskite)では 3以下 それ以外(例:Olivine, quartz)では傾き4以上
The outer core density: lower by 7 - 10 % than that of pure iron (Anderson and Issak, 2002; Shanker et al. , 2004). High solubility of O and Si in molten iron may explain the density deficit of the core. 8
After Fiquet et al. (2004) Fe Theory (Steinle-Neumann Et al. (2001) NRIXS (Mao et al. (2001) at 300 K IXS Fiquet et al. (2001) at 300 K PREM inner Shock core Brown and Mc. Qween (1986) at 3000 -6000 K Discrepancy: IXS X線非弾性散乱 and Shock vs NRIXS 核共鳴X線非弾性散乱 Temperature effect on Birch law ? 温度依存性 40
4. Birch’s Law • 核物質のVP 40. 0 42. 0 核物質のVPはBirch’s lawに 従う 44. 9 55. 8 35. 9 49. 9 Badro et al. (2007) x: 鉄の核中での体積比率 44. 0
BL 35 XU Optics: Baron et al. (2000) Si (9, 9, 9) and Si(11, 11) Instrument configuration X-ray beam size 70 x 70 μm 2 41
670 km Bulk sound velocity Vf (km/sec) 400 km 670 km Mg 3 Al 2 Si 3 O 12 220 km P Mg 2 Si. O 4 T spinel garnet Fe 3 Al 2 Si 3 O 12 olivine Fe 2 Si. O 4 Density g/cm 3 温度、圧力、組成、相転移依存性」
復習 670 km Bulk sound velocity Vf (km/sec) 400 km 670 km Mg 3 Al 2 Si 3 O 12 220 km P Mg 2 Si. O 4 T spinel garnet Fe 3 Al 2 Si 3 O 12 olivine Fe 2 Si. O 4 Density g/cm 3 温度、圧力、組成、相転移依存性」
ln. Vb = (dc-1)/2 = constant = 1. 5~2. 5, where dc~4 lnr P の証明 ln Vb=(ln. Ks-lnr)/2 ゆえに ln. Ks -1 lnr ln. Vb = lnr P = (dc-1) ここで dc:Anderson-Gruneisen Constant 温度によらず一定 dc = ln. Ks lnr =P ln. Ks = ln. V P a ln. Ks T = constant P
圧力が変化する場合のVbとrの変化(等温) ln. Vb ~ lnr T (Ks’-1) ~ 1. 5~2. 5 ln. Vb lnr = T = lnr { ln Ks-ln r T ln. Ks -1} lnr T ln. Ks = Ks’ KT/Ks =Ks’ =4~6 lnr T
状態方程式 Equation of State 通常の固体の状態方程式 Birch-Murnaghanの状態方程式 (Birch-Murnaghan equation of State やわらかい物質に対する状態方程式 Vinetの状態方程式 (Vinet Equation of State)
Mie’s potentialからBirch-Murnaghanの状態方程式を導くこと。
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